Bushings for locating two adjaent parts



H. w. PLOCH ETAL 3,381,554

BUSHINGS FOR LOCATING TWO ADJACENT PARTS May 7, 1968 Original Filed Oct.30, 1964 FIG.|.

FIG.

INVENTORS HENRY W. PLOCH ROBERT T. GRAVLIN BYRON W. PEASE United StatesPatent 3,381,554 BUSHINGS FOR LOCATING TWO ADJACENT PARTS Henry W.Ploch, Robert T. Gravlin, and Byron W. Pease,

St. Louis, Mo., assignors to McDonnell Aircraft Corporation, St. Louis,Mo., a corporation of Maryland Continuation of application Ser. No.407,790, Oct. 30, 1964. This application June 30, 1967, Ser. No. 655,2622 Claims. (Cl. 77-62) ABSTRACT OF THE DISCLOSURE Bushings for locatingtwo adjacent parts in a predetermined registered relation to each otherwhere one of the parts is a jig or fixture and the other part is thestock that is to be machined or otherwise formed into a production part.

This application is a continuation of our prior application, Ser. No.407,790, filed Oct. 30, 1964, now abancloned.

The present invention relates to locating type bushings, and moreparticularly to a bushing adapted to afford angular reference from afixed point on manufacturing jigs or fixtures that comprise productiontools generally. More specifically, the invention relates to bushings toprovide angular location from a fixed point with a relatively widetolerance of the radial distance therefrom.

Various jig fixtures and similar tools have been previously designedwith locating holes which are used for cating stock material that willbecome production parts and in which a pair of fixed reference holes orpoints are provided. Heretofore such jigs or fixtures or tools requirereference holes and bushings therefor at extremely close tolerance tomaintain appropriate tolerance on production parts. Thus, in the pastwhen one of the holes on a production part is out of tolerance with thetool, it will not readily fit over the usual mounting pins inserted inthe reference or locator holes in the tool, hence the tool has to beredrilled. Likewise, it is essential that the part locator holes bedrilled with close tolerances to permit the template to fit the locatorhole. Thus, all previous parts or members, whether guide templates,fixture tool or not, for fixing the position of production parts haveeither prevented close tolerances in locating such holes or requiredexcessive cost to achieve that end.

, The present invention avoids the tolerance difliculty of prior arttechniques by providing a first part having a first bushing with acircular hole, or just a plain hole and a second or locator bushing at aspaced position relative to the first bushing or hole, but with arelztively wide tolerance in direction of movement toward or therefromfor aligning locator points by which the production part is mounted onthe first part. This is achieved by the bushing having an elongated oroval bore rather than a circular bore as in the first bushing or hole.The tolerance along the line of tolerance is held by providing a key pinfor the bushing which holds the bushing aligned along the long diameteror major axis of the oval bore. The key pin is seated in the externalsurface of the bushing. The oval bushing and key pin, if desired, may befusion welded to one another. The first part is drilled with a key pinhole and a bushing hole in the same machine that drills the round holefor a fixed key pin. If the locator holes in the production part foraccommodating the mounting pins for the first part are at the pnopertolerance then the elongated bushing is unnecessary. However, where thelocator holes for the mounting pins in the production part are notwithin the tolerance of the holes in the first part, the elongatedbushing is used.

The elongated bushing may be provided with a diametrical keyway or slotfor a key pin slidably mounted thereon. The diametrical keyway islocated on the axis of the long diameter of the bushing, thus providingmovement in a radial direction with respect to the position of thecircular bushing.

It is therefore an object of the invention to provide a first part withan improved arrangement of holes and bushing for association withproduction parts that have pro-formed mounting holes therein, and toutilize the improved bushing to take care of alignment between the firstpart and the production part upon the insertion of mounting pins in theholes and the bushing.

It is another object of the invention to provide an improved bushingwhich fixes a predetermined angular location for a production part froma fixed point bushing, yet accommodates radial displacement ormisalignment of locating holes in a production part throughout arelatively wide tolerance.

It is another object of the invention to provide a floating locator pinbushing for maintaining a fixed angular displacement about a fixedpoint, but which permits radial displacement between the locator pin andthe fixed point.

Another object of the invention is to provide a bushing for use in amember for production parts, which member has an oval bore therein andsupports a locator pin free to slide on a diametrical dowel key alongthe long or ma jor diameter of said oval bore, and includes a dowel pinto fix the bushing with the long diameter of the bore on a radial linewith a fixed point bushing.

These and other objects and advantages of the invention will become moreapparent from the ensuing description along with the appended claims inconjunction with the drawings wherein:

FIG. 1 is a top view of one of the bushings appertaining to theinvention;

FIG. 2 is a side view of the bushing in FIG. 1;

FIG. 3 depicts a fixture base or member employing the bushing of FIG. 1appertaining to the invention;

FIG. 4 is a top view of another bushing modified to include a floatinglocator pin;

FIG. 5 is a cross sectional view of FIG. 4 taken along line 55;

FIG. 6 is a view illustrating a fixture base or member for a productionpart fitted with the bushing of FIG. 4 appertaining to the invention;and

FIG. 7 is a cross sectional view of FIG. 6 taken along line 77 thereof.

Before proceeding with a description of the drawings it should be notedthat the present improvement is applicable to fixtures that are used inconjunction with materials to be worked upon by tools for converting thematerials into production parts. It is known in this art to have a jigor sub-base form provided with a surface on which a production part canbe mounted. The sub-base usually has many holes in patterns that can bevariously selected to locate a production part on the fixture base in apredetermined desired position. Pins are used to secure the part to thefixture base, and the troubles heretofore have been that unless extremeaccuracy is achieved, one of the pins may not fit because overlyingholes in both the sub-base and the fixture base are not sufiicientlyclosely aligned. The present locator bushing solved this problem byhaving a slot instead of a hole, with the slot aligned with its majordiameter on a line through the center of one of the sub-base holes thatis to be engaged by a pin. Thus the pin for the slotted locator bushingcan easily be located within the limits of the major diameter, to fitthe sub-base hole without allowing deviations of an angular characterand can still fit in the sub-base hole. This concept is depicted in FIG.3.

When a piece of material to be converted to a production part is mountedon the fixture base, the fixture base is provided with a fixed pin andwith a floating pin carried in a locator bushing. The material isprovided with spaced plain holes at about the spacine of the fixed andfloating pins, whereby the spacing of the lain holes Will quickly bematched by the fixed and floating pins. Since the fixed and floatingpins have a preselected relation to rectangular coordinates, theproduction part will be located in a desired position.

Referring now to FIGS. 1 and 2 the bushing 1 appertaining to theinvention has a circular outer diameter and an oval inner bore 2. Alongthe long axis of bore 2 at the outer surface of bushing 1 is an arcuatekeyway 3 which has a key pin 4 fixed thereto. Alternatively, bushing 1and key pin 4 may be separately applied in which case the key pin isheld in arcuate key way 3 by the body of the surrounding material.

Referring to FIG. 3, a typical production member or fixture 1th isdepicted with a series of screw mounting holes 11 which are to bedrilled in all production plates with a specific close tolerancerelationship therebetween. Member has a fixed point bushing 12 ofsuitable hardenable material with an opening to receive mounting pin 13providing a fixed point by which the two parts are initially joined. Thebushing 12 has a plain round hole therein which can also berepresentative of a plain hole directly in the part 10 without aseparate bushing. A second bushing at a fixed angular position frombushing 12 is seated in a suitable bore 14 with key pin 4 seated partlyin arcuate keyway 3 and partly in the pin bore 15 of the member 10. Inthis manner, the long diameter or major axis of bore 2 in bushing 1 isradially aligned at the fixed angular displacement from the center ofthe hole for pin 13 as represented by radial line 16. Since the pin 13in bushing 12 fixes one end of the member 10 it is only necessary toinsert another pin or dowel in the elongated bore 2 of bushing 1 topositively fix the position of the whole member 10.

Referring now to FIGS. 4 and 5, the floating mounting locator pin isfixed by retainer pin 21 in a cross bore 22 of locator pin 20 and seatsin apertures 23 and 24 of bushing 25. Apertures 23 and 24 supportretainer pin 21 aligned with the major diameter of bore 26 in bushing25. Arcuate keyway 27 is provided in the outer surface of bushingaligned with the major diameter of bore 26 so that a dowel pin 4' (FIG.6) can be used to orient the bushing. The pin 20 may have some tolerancevariations with its supporting cross pin 21, but this is not detrimentalas this type of tolerance will allow the outer end of the pin 20 somedegree of tilt for easy insertion into a production part as will bedescribed.

Referring now to FIGS. 6 and 7 there is illustrated a production part 30mounted on a member 10 by pin reception holes 31 and 32 therein. Fixedpoint locator pin 13 seated in bushing 12 fixed in the member 10projects into locating hole 31 in part 30. Locating member hole 32 inthe part is to determine the angular position on the member 10 and thisis done with pin 20 of bushing 25 seated therein. Pin 20 is held byretainer pin 21 and is depicted at the average radial displacement fromfixed point 13 to be received in hole 32. From the foregoing, it will beappreciated that the distance between pins 31 and 32 need not be figuredto a close tolerance as locator pin 20 in bushing 25 may adjust radiallyto engage locating hole 32 so long as holes 31 and 32 are properlydrilled in the production part.

From the foregoing it will be appreciated that the invention provides afirst member or part with a fixed point bushing and a variable pointbushing at a fixed angular displacement from the fixed point bushing andthe variable point bushing. Hence, the member or part appertaining .tothe invention may be utilized to provide the appropriate relationshipfor production operations, with respect to locating holes in theproduction part.

While the member 10 in FIG. 3 is shown separately from the member 30 inFIG. 6, it is understood by those skilled in this art that the members10 and 30 may be the same. In this event, the bushings 12 and 1 areutilized to accurately position the member 10 or 30 on a subbase orother larger part (not shown). The pin to be inserted in bushing 12 willfix the position of the member except for angular location, and the pinto be inserted in bushing 1 will fix the angular location. The elongatedbore 2 avoids having to go to the expense of accurate drilling two holeswhen accurate location of one hole and the use of locator bushing 1 willsuffice.

The member 10 or 30 is mounted on its sub-base (not shown) as abovedescribed, and before so mounting it is provided with a fixed pin 13 andwith a bushing of the type shown in FIGS. 4 and 5. The pin 13 and thebushing pin project to the same side to be in position for quicklyreceiving a workpiece or production part 30. The part 30, and allsimilar parts, needs to have two holes provided therein which are spacedto roughly match the spacing of pins 13 and 20. Since pin 20 has radialmovement relative to pin 13 it can easily adjust to fit the tolerancevariations in the holes 31 and 32. The work performed on parts 30 willin no way be affected by the pins 13 and 20.

Therefore, it will be understood and appreciated that variousmodifications and changes to the invention are apparent and such changesand modifications are deemed to be within the scope and spirit of theinvention which is limited only as necessitated by the scope of theappended claims.

What is claimed is:

1. The improvement in means for locating two parts to be connectedtogether in a predetermined position said improvement including one parthaving a pair of round holes spaced apart, a bushing inserted in one ofsaid holes and having an elongated opening therein with major and minoraxes, a key element engaged in said one part and holding said bushing inpredetermined angular position with said major axis aligned with thecenter of the other of said holes, said major axis being located tocoincide with the desired angular position, a first pin carried in oneof said holes, a second pin floatingly mounted in said bushing to havelimited movement in a direction toward and away from said first pin, andthe other part having pin receiving openings therein spaced apart tosubstantially match the spacing between said hole and said bushing insaid one part, said elongated opening in said bushing providing fortolerance variations in the spacing of said openings in said other part.

2. The improvement in means for locating two parts to be connectedtogether in predetermined registration: said improvement including onepart having a pair of spaced apertures therein, a bushing mounted in oneof said apertures, the other of said apertures having a plain roundopening therethrough and said bushing having an elongated openingtherethrough defined by major and minor diameters in which the majordiameter is directed so as to be in alignment with substantially thecenter of the plain hole in said one aperture; a key element engaged insaid one part and a margin of bushing for holding the latter bushingagainst angular movement and with its major diameter in said alignment;the other part having openings therein spaced apart to substantiallymatch the spacing between the openings in said aperture and bushing insaid one part; and pins inserted in said bushing and openings in saidtwo parts, said pin mounted in said elongated opening of said bushingbeing relatively free to move only in the direction of said majordiameter whereby said parts are brought into predetermined overlyingregistration.

6 References Cited UNITED STATES PATENTS 2,492,528 12/1949 Huebner33-1845 FRANCIS S. HUSAR, Primary Examiner.

